Coverage.py 4.0a3

Lots of things happening in coverage.py world these days. Turns out I broke
the XML report a long time ago, so that directories were not reported as
packages. I honestly don’t know why I let that sit for so long. It’s
fixed now, but I feel bad that I’ve ignored people’s bug reports and pull
requests. I’ll try to be more responsive.

The fix is in coverage.py v4.0a3.
Also, the reports now use file names instead of a weird hybrid. Previously,
the file “a/b/c.py” was reported as “a/b/c”. Now it is shown as “a/b/c.py”.
This works better where non-Python files can be reported, so we can’t assume
the extension is .py.

Also in the XML report, there’s now a configuration setting to determine
the directory depth that will be reported as packages. The default is that
all directories will be reported as packages, but if you set the depth to 2,
then only the upper two layers of directories will be reported.